This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Gamma-aminobutyric acid (GABA) and Glutamate are the two major neurotransmitters of the brain. Their levels are also altered by disorders of the central nervous system (CNS) and several drugs acting on the central nervous system (CNS) mediate their effects by changing GABA and Glutamate levels. Hence, GABA and Glutamate serve as surrogate markers for diagnosis, treatment, and evaluation of therapeutic efficacy. Existing approaches for measuring regional changes in GABA and Glutamate in humans include positron emission tomography (PET), single photon emission tomography (SPECT) and Magnetic Resonance Spectroscopy (MRS). The shortcomings of PET and SPECT are low resolution and radiation exposure, which limits applicability to functional studies. MRS on the other hand is able to detect GABA and Glutamate in-vivo, but requires complicated spectral editing techniques and has limited spatial and temporal resolution. In this project, we are developing a novel, noninvasive, nonradioactive and high resolution approach for imaging brain GABA and Glutamate exploiting chemical exchange saturation transfer (CEST) effect from the amine proton groups on GABA and glutamate.